On February 7, 1952, while shopping at Hoggly Woggly, Dr. Emmett Brown accidentally knocked out a man who turned out to be a wrestler for Small Town Wrestling. He was given the chance to to be a wrestler for Small Town Wrestling himself under the name "Brain-Buster Brown" against Mad Maximus. However Emmett decided not to follow through with it, to continue to pursue science, and never showed up for the fight.
However, that was changed in 1992, when Verne Brown found out that his father could have been a wrestler. Verne and his brother Jules got Marty McFly to drive them back in time to the date of the match, February 15, 1952, to convince Doc to go through with the match.
As soon as Doc entered the ring, he was hit on the head with a microphone. He lost his memory, and upon seeing his outfit, thought he was a superhero. He began referring to himself as Mega-Brain-Man, and tried to perform heroic deeds, which ended up causing more trouble than before his intervention.
After several misdeeds, Doc finally arrived at the ring, and had the sense knocked back in to him. He lost the match, and went back to his pursuit of science. Marty, Verne, and Jules headed back to 1992, where they found that the events didn't do much to change Doc, other than changing his story about his short wrestling career. However, the experience gave Verne the courage to stand up to bullies.